The borosulfates are heteropoly anion compounds which have sulfate groups attached to boron atoms. Other possible terms are sulfatoborates or boron-sulfur oxides. The ratio of sulfate to borate reflects the degree of condensation. With [B(SO4)4]5- there is no condensation, each ion stands alone. In [B(SO4)3]3- the anions are linked into a chain, a chain of loops, or as [B2(SO4)6]6− in a cycle. Finally in [B(SO4)2]− the sulfate and borate tetrahedra are all linked into a two or three-dimensional network. These arrangements of oxygen around boron and sulfur can have forms resembling silicates. The first borosulfate to be discovered was K5[B(SO4)4] in 2012 by the research group of Henning Höppe, although the compound class as such had been postulated already in 1962 by G. Schott and H. U. Kibbel. Over 80 unique compounds are known as of 2024.
They are distinct from the borate sulfates which have separate, uncondensed sulfate and borate ions.
Related compounds include boroselenates, borotellurates, and also boroantimonates, borogallates, borogermanates, borophosphates, boroselenites and borosilicates.
Formation Borosulfates are formed by heating boric oxide, oleum, or sulfuric acid, with metal carbonates. The degree of condensation is varied with the ratio of oleum to sulfuric acid. Pure oleum is more likely to yield compounds with disulfate groups.
Reactions When heated to around 500 °C the borosulfates decompose by emitting SO3 vapour and form a metal sulfate and boric oxide.
List chemmwcrystal system space groupunit cell Åvolumedensitycommentreferencesboron sulfate229.74monoclinicC2a=7.7600, b=4.1664, c=8.6134; β=94.785°; Z=2277.512.749no cations; 3D meshsuperacidP4/ncca=9.1377, c=7.3423; Z=4monoclinicP2/ca=15.697, b=11.4362, c=8.5557; β=90.334°Pca=7.635, b=9.342, c=8.432; β=92.55°3D network, like tectosilicateorthorhombicP212121a=10.862, b=10.877, c=17.769orthorhombicP21/ca=8.0191, b=10.2111, c=15.0401monoclinicC2/ca=23.856, b=7.3507, c=12.3235; β=98.724(2)°; Z=82136.12.58colourlessP4/ncca=9.1980, c=7.2458decomposes at , proton conductormonoclinicCca=11.4403, b=14.9439, c=13.8693; β=93.662°271.38monoclinicC2a=11.3685, b=6.5541, c=12.8328; β=106.247°; Z=4918.01.964SHG 1.1 × KDP; min PM wavelength 252 nm; decompose 300 °C; UV edge 184 nmmonoclinicP21/ca=7.7506, b=6.6685, c=24.355; β=92.562°; Z=41257.52.000white343.12orthorhombicIbca a=7.2858, b=14.7048, c=22.7052; Z=82433.21.928decomposes chainsmonoclinicP2/ca=5.434, b=7.570, c=7.766; β=99.74°monoclinicP21/ca=10.949, b=8.49, c=12.701; β=110.227°; Z=4orthorhombicPbcaa=11.6569, b=9.4094, c=17.4833; Z=81917.62.431birefringence Δn = 0.07 @ 589.3 nmNa3B3S2O11(OH)2triclinicPa=6.5282 b=6.6711 c=12.0045 α=93.927° β=99.502° γ=94.278°orthorhombicPca21a=10.730, b=13.891, c=18.197orthorhombicP212121a=8.624, b=9.275, c=16.671whiteLi2NaB3S2O12monoclinicP21/ca=11.6720 b=8.2574 c=9.6126 β=97.940°birefringence 0.057 at 546.1 nm; UV edge 184 nm711.22trigonalPa=8.0165 c=7.4858 Z=1416.622.835colourless 711.22hexagonalPa = 13.9196, c = 7.4854, Z = 312532.821colourless 430.17monoclinicC2/ca=17.443, b=5.3145, c=14.2906; β=126.323°; Z=41067.32.677phyllosilicate structure colourless decomposes monoclinicP21/na=7.9100, b=8.0815, c=9.0376; β=111.37°; Z=2269.012.667colourless decomposes 706.94triclinicPa=7.9609, b=7.9671, c=9.2343; α=64.959°, β=89.228°, γ=60.054°444.962.638200K706.94Ra=7.9620, c=24.4231; Z=31340.842.627room temperatureP4/ncca=8.9739 c=7.4114 monoclinicCca=11.3368, b=14.66, c=13.6650; β=94.235°; Z=8313.50monoclinicC2a=11.2631, b=6.4339, c=12.649; β=105.707°; Z=4882.42.360colourless; UV edge 182 nmK3B3S2O11(OH)2triclinicPa=7.0282 b=7.1559 c=12.3096 α=89.423° β=79.065° γ=86.344°pentapotassium borosulfateP41a=9.9023, c=16.18711687.22.471first discoveredI2/aa=14.524, b=7.3916, c=15.78.57, β=115.499° 1529.62.399orthorhombicIbca a = 7.074, b = 14.266, c = 22.58monoclinicI2/aa=14.524 b=7.3916 c=15.7857 β=115.50K[B(SO3Cl)4]triclinicP1a=10.513 b=10.838 c=10.965 α=99.21° β=135.48° γ=97.15° Z=2chlorosulfate; moisture sensitiveNa4KB(SO4)4triclinicPa=6.993 b=12.124 c=15.950 α=88.549° β=86.823° γ=89.609°monoclinicP21/ca=5.5188, b=15.1288, c=13.2660; β=92.88°sheetmonoclinicP21/na=8.0435, b=7.9174, c=9.3082; β=110.94° Z=2553.63colourless833.74trigonalPa=8.1086, c=7.7509; Z=1441.33.137colourless833.74trigonalPa=13.9196 c=7.4854monoclinicC2/ca=17.4254, b=5.3397, c=14.3214; β=126.03°; Z=4269.402.860pinkmonoclinicP21/na=7.8892, b=8.1042, c= 9.0409; β=111.29°; Z=2269.292.803pink849.70trigonalPa=7.991, c=7.669; Z=1418.03.376pink848.82trigonalPa=7.9359 c=7.4398 Z=1405.773.474yellowtriclinicPa=5.3096, b=7.0752, c=11.1977; α=81.154°, β=80.302°, γ=80.897°cyclictriclinicPa=5.2470, b=7.1371, c=7.9222; α=73.814°, β=70.692°, γ=86.642°chainmonoclinicP21/na=8.0435, b=7.9174, c=9.3082; β=111.26°; Z=2534.36colourless875.46trigonalPa=7.9971, c=7.4895; Z=1414.813.505colourlessRb[B(SO4)2]tetragonalP4/ncca = 9.1823 c = 7.4559 Z = 4628.643.05406.24monoclinicC2a=11.3127, b=6.5152, c=12.971; β=105.411°; Z=4921.62.928colourless; UV edge 190 nmorthorhombicIbcaa=7.2759, b=14.794, c=22.637orthorhombicPnmaa=8.0415, b=10.647, c=20.425 tetragonalP43212a=10.148, c=16.689; Z=4band gap 3.99 eVP63/ma=6.502, c=19.02; Z=2white743.8monoclinicP21a=7.5551, c=14.560, c=7.5517; β=90.2372°; Z=2transparent743.8tetragonalIa=7.6128, c=14.631; Z=2at 500K; SHG 1.1 × KDPNa4RbB(SO4)4monoclinicP21/na=7.0493 b=12.171 c=16.011 β=93.707°493.48orthorhombicPnmaa=12.574, b=12.421, c=7.319; Z=41143.12.867decomposes 573.54monoclinicP21/na=7.470, b=15.334, c=12.220; β=93.29°; Z=41397.52.726orthorhombicPnmaa=1657.3, b=12.037, c=4.39484 617.36monoclinicP21/ca=11.3309, b=7.1482, c=19.355; β=106.878°; Z=4 1500.12.73colourless; Sr in 9 coordination by sulfate oxygensmonoclinicC2/ca=13.5172, b=11.3941, c=10.8994; β=93.447°cyclicmonoclinicP21/ca=7.2686, b=12.7802, c=11.4930; β=101.343°; Z=21046.82.64bluetetragonalP41a=13.8210, c=21.724; Z=84149.72.66bluemonoclinicP21/ca = 6.7061 b = 16.0198 c = 8.1681 β = 94.923° Z = 2 874.272.55redAg[B(SO4)2]P4/ncca=8.6679 c=7.2897Ag[B(S2O7)2]monoclinicP21/ca = 9.507, b = 9.601, c = 11.730, β = 98.35° Z=41059.32.953colourlessCd[B2(SO4)4]Cd[B2O(SO4)3]438.20orthorhombicPnmaa=8.9692 b=11.520 c=8.7275 Z=4901.83.23colourlessCd4[B2O(SO4)6]trigonalPa=8.2222 c=7.9788 Z=1467.143.78colourlessLiSb[B(SO4)2]4tetragonalIa=11.7805 c=8.1027 Z=21124.492.777NH4Sb[B(SO4)2]4monoclinicC2a=16.6782 b=8.1140 c=11.8248 β=134.8°1135.62.78NOSb[B(SO4)2]4monoclinicC2a=16.6672 b=8.1228 c=11.7741 β=134.8° Z=21130.212.83NaSb[B(SO4)2]4tetragonalIa=11.7889 c=8.1190 Z=21128.362.815KSb[B(SO4)2]4monoclinicC2a=16.619 b=8.122 c=11.723 β=134.55° Z=21127.62.865RbSb[B(SO4)2]4monoclinicC2a=16.6673 b=8.1124 c=11.8308 β=134.7° Z=21136.452.978AgSb[B(SO4)2]4tetragonalPa=11.7994 c=8.1323 Z=21132.233.05(I4)[B(S2O7)2]2triclinicPa = 11.3714 b = 11.5509 c = 12.7811 α = 68.638° β = 68.275° γ = 64.626° Z=21366.162.999orange-brownCs2B4SO10501.12monoclinicC2a=11.4012 b=6.5997 c=13.5702 β=103.934° Z=4919.043.359colourless; UV edge 189 nmCs2[B2O(SO4)3]monoclinicP2/ca=14.765 b=6.710 c=12.528 β=104.50Cs3HB4S2O14P63/ma = 6.5648, c = 19.5669 Z=2Cs3H2[BOB(PO4)3]monoclinicP21/ca=8.2436 b=6.7387 c=24.414 β=92.713° Z=41354.73.538proton conductorCs[B(SO4)(S2O7)] monoclinicP21/ca=10.4525, b=11.319, c=8.2760; β=103.206; Z=4Cs3Li2[B(SO4)4]monoclinicP21/na=13.7698 c=8.2376 c=13.9066 β=91.778Na3Cs2B(SO4)4monoclinicP21/na=13.7654 b=8.2281 c=13.9021 β=91.741°Cs3Na2[B(SO4)4]monoclinicP21/ca=13.6406 b=7.9475 c=13.9573 β=990.781CsK4[B(SO4)4]P43212a=9.9433 c=16.881CsSb[B(SO4)2]4tetragonalPa=11.916 c=8.0845 Z=21147.983.085Ba[B2(SO4)4] orthorhombicPnnaa = 12.791, b = 12.800, c = 7.317 Z = 4Ba[B2O(SO4)3] orthorhombicPnmaa=17.1848 b=12.3805 c=4.4226 Ba[B(S2O7)2]2monoclinicI2/aa = 11.6077, b = 8.9144, c = 21.303, β = 104.034° Z = 4chainsLa2[B2(SO4)6]monoclinicC2/ca=1379.2 b=1158.9 c=1139.5 β=93.611cyclicCe2[B2(SO4)6]monoclinicC2/c13.740 b=11.5371 c=11.3057 β=93.661cyclicPr2[B2(SO4)6]monoclinicC2/ca=13.711 b=11.5305 c=11.2643 β=93.668cyclicNd2[B2(SO4)6]monoclinicC2/ca=13.6775 b=11.51.34 11.2046 β=93.5909cyclicSm2[B2(SO4)6]monoclinicC2/ca=13.633 b=11.492 c=11.112 β=93.567cyclicEu2[B2(SO4)6]monoclinicC2/ca=13.602 b=11.470 c=11.050 β=93.465cyclicGd2[B2(SO4)6]monoclinicC2/ca=13.5697 b=11.4426 c=11.0271 β=cyclicTb2[B2(SO4)6]monoclinicC2/ca=13.5601 b=11.42.48 c=10.9881 β=93.534cyclicDy2[B2(SO4)6]monoclinicC2/ca=13.568 b=11.425 c=10.9703 β=93.540cyclicHo2[B2(SO4)6]monoclinicC2/ca=13.505 b=11.409 c=10.921 β=93.453cyclicEr2[B2(SO4)6]monoclinicC2/ca=13.551 b=11.411 c=10.882 β=93.41cyclicTm2[B2(SO4)6]monoclinicC2/ca=13.4981 b=11.3617 10.8327 β=93.4500cyclicYb2[B2(SO4)6]monoclinicC2/ca=13.495 b=11.3452 c=10.7961 β=93.390cyclicLu2[B2(SO4)6]monoclinicC2/ca=13.469 b=11.364 c=10.799 β=93.369cyclicLiLu[B(SO4)2]4tetragonalIa=11.7160 c=8.0395 Z=21103.542.990NaLu[B(SO4)2]4tetragonalIa=11.7060 c=8.0610 Z=21104.603.036KLu[B(SO4)2]4tetragonalIa=11.7369 c=8.0476 Z=21108.603.073RbLu[B(SO4)2]4tetragonalPa=11.779 c=8.034 Z=21114.623.195CsLu[B(SO4)2]4tetragonalPZ=2contained H3O+[Au3Cl4][B(S2O7)2]monoclinicP21/ca=10.6266 b=12.7938 c=12.7373 β=99.322° Z=41708.824.259yellow[Au2Cl4][B(S2O7)2](SO3)orthorhombicFddda=13.1467, b=17.8576 c=31.711 Z=167444.83.49metallic grey or transparent green dependent on polarizationTlSb[B(SO4)2]4monoclinicC2a=16.689 b=8.1093 c=11.859 β=134.72 Z=21140.53.31Pb[B2(SO4)4]613.05orthorhombicPnnaa=12.516 b=12.521 c=7.302 Z=4 114.433.558loop chainPb[B2O(SO4)3]orthorhombicP21/ma=4.4000 b=12.1019 c=8.6043 Bi2[B2(SO4)6]659.08orthorhombicC2/ca = 13.568, b = 11.490, c = 11.106 Z=41728.83.894(H3O)Bi[B(SO4)2]4 1039.72tetragonalIa=11.857, c=8.149 Z=21156.842.99colourless; non-linear optical(NH4)Bi[B(SO4)2]4tetragonalIZ=2 a=11.8746 c=8.13601147.23.007(NO)Bi[B(SO4)2]4tetragonalIa=11.8277 c=8.1315 Z=21137.53.068(NO2)Bi[B(SO4)2]4tetragonalIa=11.9081 c=8.1160 Z=21150.873.078LiBi[B(SO4)2]4tetragonalIa=11.8189 c=8.1235 Z=21134.743.008NaBi[B(SO4)2]4tetragonalIa=11.8863 c=8.1176 Z=21146.893.022KBi[B(SO4)2]4tetragonalIa=11.835 c=8.1421 Z=21140.443.086RbBi[B(SO4)2]4tetragonalPa=11.883 c=8.1315 Z=21148.183.200CsBi[B(SO4)2]4tetragonalPa=11.964 c=8.120 Z=21162.183.297(UO2)[B(SO4)2(SO3OH)]569.52triclinicPa=5.448 b=7.021 c=13.522 α =92.248° β =95.347° γ =101.987° Z=23.762green(UO2)2[B2O(SO4)3(SO3OH)2]1058.23monoclinicP21/na=10.872 b=11.383 c=14.812 β=92.481 Z=43.838yellow
References
External links An introduction to borosulfates is available as ACS Spring Meeting video of 2021.